May 2017: A punishing drought. May 2018: All the rain we needed.

It's when bay area residents can expect water usage restrictions and headlines warning of dangerously low reservoir levels. It's when local governments issue burn notices to reduce the wildfire threat of dry ground.

This time last year, Tampa Bay was enduring one of Florida's worst droughts.

Not so this year.

Rain fell in historic proportions last month, making May one of the wettest on record locally. Subtropical Storm Alberto led to rainfall in 17 out of the last 19 days in Tampa last month. It was the sixth wettest May on record in Tampa, the second wettest in St. Petersburg and the wettest ever in Lakeland.

The extra rainfall has raised reservoir levels, temporarily reduced the wildfire threat and lifted Florida from drought, weeks before the summer rain engine usually brings relief.

But all that extra water comes with its own problems.

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During the winter months, when rain is sporadic and river levels drop, the utility that manages the bay area's drinking water supply leans on its reservoir.

Tampa Bay Water uses the Alafia River, Tampa Bypass Canal and other bodies of water to replenish the 15.5-billion gallon C.W. Bill Young Regional Reservoir.

During last year's drought, the reservoir fell to about 5 billion gallons. This year, it sits at 11 billion.

"We typically don't start putting water back in it for another couple weeks," Tampa Bay Water spokesman Brandon Moore said. "So this rain has really helped."

When the reservoir is depleted this time of year, governments start issuing restrictions on watering lawns and washing cars.

Bay area residents haven't seen those kinds of warnings this year.

Most places around Tampa Bay and Central Florida receive between two and four inches of rain during a typical May. But last month, many locales saw at least three times their average rainfall.

Tampa received 7.73 inches of rain — more than five inches above normal. St. Petersburg saw 9.68 inches of rain, almost 7.5 inches above normal.

Nothing topped Lakeland, where more than 19 inches fell. That's almost six times its May average of 3.36 inches.

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Spring is when things grow in Florida.

But that's also when the ground dries out, said Judi Tear, a mitigation specialist with the Florida Forest Service's Withlacoochee Forestry Center. Plants pull water from the ground to grow, leaving the soil barren and ready to fuel a fire.

Lightning strikes can ignite the dry ground, leading to wildfires. That's what happened last spring, Tear said, when storms delivered lightning but little rain. In 2017, much of the North Suncoast contended with wildfires for months. Not the case this year.

"We've not seen the lightning (fires) that we had last year," she said. The storms have delivered more rain, so any lightning has struck wet ground.

At the start of May, much of Florida was experiencing drought conditions. Before the stretch of rain started on May 13, many of Florida's counties registered high on the Keetch-Byram Drought Index, which measures soil moisture. High numbers mean dry soil.

By Tuesday, almost the entire state registered low scores on the drought index, mitigating — for now — the fire threat.

Fire experts are worried the summer could still be an active one for wildfires. Tear said Hurricane Irma could also impact the wildfire situation. The 2017 hurricane knocked down trees and branches, which can dry quickly. That leaves even more kindling for a fire this year.

That's because heavy rains after drought can lead to sinkholes. The water table can drop, leaving a cavern beneath the top layer of earth. Then, heavy rains can dissolve limestone, which collapses into the caverns below.

Last summer, a massive sinkhole more than 250 feet wide swallowed two houses in a Land O'Lakes neighborhood and left seven others condemned. It opened on July 14, after torrential rains ended the 2017 drought.

Oversaturation also means the ground and rivers can't hold excess water when it rains. When Alberto threatened Florida last week, forecasters worried the already heightened rivers would overflow their banks.

And wet ground makes it hard for the Forest Service to starve fires of fuel through mitigation. One of the firefighting agency's most effective tools is prescribed burns, during which workers ignite dry sources of fuel in a controlled manner to ensure they don't fuel a real wildfire.

Said Tear: "The good news is, once we catch back up on our dry days, we can catch back up on our prescribed burning."